Questions tagged [rf]
Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.
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How are S-Parameters and Reactance related, can one be calculated from the other?
I know that, for example, \$X_L=2\pi f L\$ will calculate reactance of an ideal inductor, but can this be calculated for a real component model? Given the S-Parameter values at some frequency from an ...
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How to properly handle mixed RF/digital design in HFSS 3Dlayout
I have a big design imported from Altium into HFSS 3DLayout with several RFIC that I want to simulate. RF and Digital (SPI) nets are included in this design.
I'm interested mainly in the RF side of ...
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Power (dBm) of a non return to zero modulated signal
How to calculate the power (dBm) of this signal which is fed into a receiver with an input impedance of 50 ohms?
The power in dBm formula is 10log(Vrms^2/R)/1mW and R equals 50 ohms. In this case how ...
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With given impedance matching network, how to find the possible matchable load impedance range
I have some questions regarding this schematic using Keysight ADS here. The matching network is intended to function at 13.56MHz. The shunt capacitor has a range of 150-1500pF capacitance and the ...
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How is this possible: Crystal filters for FM signals?
I am trying to make my own superhet reciever. I have achieved downconversion and I am trying to build a crystal filter that will only allow the crystal's resonant frequency through. In doing so, I had ...
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Antenna port S11(dB) > 0
I'm simulating a microstrip patch antenna in microwave office at 35 GHz.
When plotting the S11 in dB of the antenna port I get values greater than zero at frequencies below 28 GHz. How is this ...
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What is the appropriate name for a parabolic antenna with a "center mounted feed"?
How would a parabolic antenna with a "center mounted feed" be called? Below are some images which illustrate the type of parabolic antenna I'm referring to.
According to wikipedia these are ...
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Unable to interface XBEE with m3pi
I have a m3 pi pololu bot (lpc1768 controller) with a mbed slot. I want to send data from a XBEE S1 connected to my PC to the bot (through another XBEE mounted on it).
To achieve this, I've a python ...
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Method for building a test fixture for the 4294A impedance analyzer?
I have an Agilent 4294A, a 40Hz-110MHz impedance analyzer, but no test fixtures to use. Unfortunately the official test fixtures are out of my price range so I need to build some. After reading ...
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Analog television: What is the difference between the first IF and second (demodulated) IF?
I am trying to understand what kind of changes occur to a signal in the chips which sit between the tuner and, for example the FM audio demodulator.
Take the attached example - the TDA2546A. It takes ...
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Frequency Counter Input Impedance
I have been looking at RF frequency counters and noticed that they all have one port that says up to 50 MHz with an input impedance of 1 megaohm. However the +50 MHz input says 50 Ohm impedance.
If ...
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Power combiner for I-Q signals in a transmitter
I have a transmitter project to implement. Part of the project is to combine an in-phase and an out of phase (90 degree difference) signal with a center frequency at 3.5GHz. I figured I could ...
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Simple Diode Mixer Help
Edit:
Thank you for your input @Kevin White, much better results with 100 ohm injection resistors, a 1K resistor for a DC pathway and a 1K bias resistor from Anode to +5V.
I am an RF enthusiast that ...
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Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its bluetooth signal?
Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its Bluetooth signal for both transmitting and receiving data?
Can I solder this type of 2.4G antenna to boost the ...
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Achieving good S22 for RF Power Amplifier with minimum power loss
I understand that achieving a S22 can reduce the maximum power and efficiency that can be achieved in a Power Amplifier. Is there any systematic approach to achieve <-10dB S22 while minimizing the ...
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Are there any sample reference RF boards for 15 GHz? [closed]
I'm working on our RF project frequency up-to 15 GHz for our application. We are little concerned about the impedance matching, track width, signal trace routing from top to middle layer, trace ...
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The problem with sensitivity time controlled (STC) based on pin diode
I'm using sensitivity time controlled (STC) pin diodes of PN:MPP 4201A-206 for our applications. Our operating frequency from 1300 MHz to 1400 MHz.
See the schematic diagram below. As device ...
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What is the link between conjugate matching efficiency and amplifier efficiency?
In the design of a class AB amplifier, there is part of the understanding that I miss. It is well-known that the maximum power transfer is achieved when the load impedance is the complex conjugate of ...
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I want to Implement this active inductor design in my circuit
I'm trying to use the active inductor in here instead of the inductor in my class e power amplifier, however I'm having difficulties in getting the required values for the parameters in here
Cds, Cgs, ...
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Trying to build RF comb generator based on a schematic. Please help me pick types of components and figure where to purchase them [closed]
I am trying to build this RF comb generator.
I've located links for the following:
Q1 (BFS17):
https://www.aliexpress.com/item/4001097379501.html?spm=a2g0o.productlist.0.0.405918830Mab95&...
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Output reflection coefficient of a power amplifier
I'm struggling to understand the implication of a poor large signal reflection coefficient at the output of a power amplifier.
I designed a power amplifier and checked the large signal S22 (for the ...
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Motor driver blanks out AM/FM radio reception
Story
I do many restorations of 'boomboxes' (70s/80s/90s) especially the decks inside these units. Next to the common problems with belts, gears, pinch rollers, rubber rings etc there is another issue ...
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Noise factor in homemade software-defined GPS receiver
I'm building a homemade software-defined GPS receiver. I'm currently at a point where I can acquire and track strong signals but struggle to even detect weak signals.
I've ruled out problems with my ...
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How to determine the radiation pattern of a receiver antenna
I am designing a receiver antenna for a wireless power transfer application.
The transmitter is a 2m x 2m horn antenna array that transmits a power signal at a frequency of 35 GHz from 100 meters away ...
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433.2Mhz receiver for Arduino
First of all I'm quite new to the subject of electrical engineering (I'm a software engineer) especially to RF! so forgive me if I forgot something to add to this question. I've done the research but ...
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Audio noise when transmitting radio packets using the ESP32
I am building a sort of walkie-talkie using an ESP32 WROOM chip. I use the internal ADC to sample the microphone and the internal DAC to power small headphones. This all works OK, not the highest ...
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How to choose a sweep range for a known and unknown device with a VNA?
I'm trying to determine best practices for using a VNA to measure say, an antenna.
Let's say I have a known antenna with a spec sheet that says it's frequency range is between x and y. Should I set ...
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Costas Loop QPSK/4QAM
I can use a Costas Loop, modified for QPSK/4QAM and recover the frequency and phase successfully when using a pattern of all 1s or all 0s or a pattern that is repetitive for each I and Q data rail (in ...
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Class AB RF Amplifier with only one active device
I'm designing an amplifier for the 420-440MHz band. I'm looking at using the following part from Ampleon: BLP15H9S100. I'm new to doing RF amplifier work and I've been going through the design process ...
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Allow 12v power through when RF transmitter is close
I'm currently working on a project to allow 12v power through when a RF Transmitter is within a 20 foot range and shuts off then the transmitter is out of range, I'm not so concerned about the range ...
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RF high power amp bias scheme
I am using the TGA2237-SM for the TX side in a front end design. I am trying to figure out an analog method for doing the bias up and bias down procedures.
Bias up
Set gate to Vg=-5V
Increase Vg till ...
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Bandpass filter doesn't work when implementing PCB
I have been trying to make a 5th-order Chebyshev filter going from 500 MHz - 570 MHz and a 3rd-order Chebyshev filter going from 500 MHz - 540 MHz. This is my first time making a filter into a PCB.
No ...
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Diode SPICE data accuracy at high frequencies?
I'm trying to do a non-linear harmonic balance simulation on a schottky diode model MACOM MA4E1317 that according to the manufacturer is usable up to 80 GHz. I got the SPICE data and S-Parameter files ...
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Synchronized two frequency source seems to have phase drift
I have two arbitrary waveform generators which are synchronized at the external but shared 10 MHz clock. My research experiment importantly uses phase-sensitive signals.
The problem I observed is that ...
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Antenna feed trace keep it short or long?
I am designing a GPS module but am quite new to RF design. I have seen a number of people say to keep your antenna feed line as short as possible. But in the design guide of the GPS module I am using, ...
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Designing GPS matching network with TESEO and chip antenna
I am new to designing for RF and have a question regarding the design of the matching network for a GPS module I am working on.
The datasheet of the chip antenna ANT161575ST-1202A1 recommends a ...
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Isolating RF Ground is it wise?
I am designing a GPS module and I am planning to isolate the RF GND from the DC power supply GND with an inductor.
I have chosen the Murata LQW18CN4N9D0ZD because the low inductance will have low Ldi/...
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Does an antenna have to be impedance matched to its transmitter circuit or the transmission line from it?
I am still very new to RF and I am trying to understand Impedance matching, so my question could be stupid.
I have already learned the basics of it, I know how to use Smith charts, which components to ...
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How to prototype with sensitive electrical components without a PCB?
Right now I'm trying to get consistent radio operation with an NRF24L01+ and a Teensy 3.6, however in my experience working with radios they have extremely inconsistent connectivity when using ...
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Is this circuit measuring the electrical field?
I have found the following circuit on the web (https://electroclinica.org/2018/03/23/fabricacion-de-un-sencillo-medidor-de-campo-de-rf-diy/)
which claims to be an "RF field" detector/meter/...
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Interaction between half wave dipole and power supply lines in 433 MHz RF module
For a second iteration of the 433 MHz transmission between Espressif ESP8266 modules, I switched to RF modules based on the SYN115 and SYN480R devices. Largely because these work much better with the ...
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Chip antenna ANT161575ST-1202A1 layout question
I am designing a GPS module using the following chip antenna:
https://product.tdk.com/en/system/files?file=dam/doc/product/rf/rf/antenna/catalog/rf_ant_ant161575st-1202a1_summary_en.pdf
The datasheet ...
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Why are three inductors and one capacitor needed to bias this transisor (radio frequency)?
Below is the circuit. I don't understand its purpose.
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How to measure radio wave penetration and reflection through different mediums
I would like to do a few experiments to test how different EM radiation frequencies (915 MHz to 5 GHz) interact with 3D print filament materials (like PLA, PolyCarbonate, TPU, etc...). Specifically I ...
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Maximum RF power for microstrip
Microstrip line have couple parameters that we can change. It's track width (W), copper thickness (t) & substrate thickness (h).
The question is "How much RF power we can transfer by this ...
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Why is ESP32 BLE so power hungry?
The ESP32 consumes around 100-130mA when BLE is active and transmitting, while other BLE chips like nRF8001 only consume around 13mA when BLE is active and transmitting.
Am I missing something, or ...
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When to employ RF shield cover on PCBA?
During reparations and teardowns I have frequently come across PCB-mounted RF shields and covers. While I don't typically work with GHz processors or design RF modules I wonder if such covers could be ...
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What energy/fields if any is generated when radio frequency is passed through a coaxial cable?
I am new here. Just had a question wondering if someone could answer.
Let's say I have a generator that can generate RF and send it through a cable (coaxial) if I attached the end of that wire to a ...
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How to simplify matching network LC circuit
I'm relatively new to RF design, and trying to implement a Micrel reference PCB antenna design (Heli-2). I am using a MICRF113 RF transmitter at 315MHz to transmit digital data using ASK (OOK).
Here ...
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How to calculate the output resistance of the CE amplifier, which has only a coil in its collector?
In order to be able to match the impedance, it is necessary to know the output resistance of the amplifier.
In radio frequency amplifier circuits, there is usually a coil in the collector instead of a ...
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